1. Technical Field
The present invention relates to a signal processing apparatus, a digital filter, and a recording medium.
2. Related Art
A signal processing apparatus generates a compensating signal using a complex number signal of a digital signal when compensating a non-linear distortion of the digital signal. Hilbert transform is known as a method to convert a digital signal into a complex number signal. Hilbert transform is described in Patent Document No. 1.
Patent Document No. 1: Japanese Patent Application Publication No. 2005-233946
A signal processing apparatus can perform Hilbert transform on a digital signal using a Hilbert filter that uses a digital signal processing circuit. The Hilbert filter is a type of band pass filter, whose frequency characteristic is defined according to the number of taps and the tap coefficient of the digital signal processing circuit, etc. So as to apply the Hilbert filter to various frequency bands, the number of taps should be increased, which unfavorably increases the circuit size.